1. Field of the Invention
This invention relates to a method and apparatus for controlling digitally operated equipment.
2. Description of the Prior Art
Typical techniques of controlling digitally operated equipment such as radio receivers, transmitters, transceivers and synthesizers employ separate switches for bandswitching, and tuning knobs for coarse and fine tuning. The operator by manipulating switches and knobs tunes the digital equipment to the desired frequency. In such equipment, the frequency is obtained by separate manual actions to switch to the frequency band, then to adjust the coarse knob for the approximate frequency and finally to adjust the fine knob to the actual frequency.
For example, U.S. Pat. No. 3,665,323 entitled "Proportional Digital Control for Radio Frequency Synthesizer," issued May 23, 1972, to Max E. Peterson, describes a system for tuning manually a frequency synthesizer with one three-position switch and one fine tuning dial. Magnetic or optical encoders are used to sense the movement of the tuning dial. Since the fine tuning dial requires 1,500 revolutions of the dial to tune through a band of 0 to 15 MHz, a three-position switch is provided to select each of three portions of the total band in which the fine tuning knob is operating to reduce the number of revolutions required for each tuning band.
An article, entitled "Synthesizer Designed for Bench Use," published in Electronics, Apr. 14, 1977, pages 151 to 152 describes another prior art frequency synthesizer. Tuning is achieved with one knob, and two push buttons. To tune to a desired frequency, the knob whose movement is sensed optically, is first operated with one push button and then with the other push button to provide coarse and fine tuning.
The prior art tuning systems do not provide a single control for tuning.